rollup.config.js

import svelte from 'rollup-plugin-svelte';
import resolve from '@rollup/plugin-node-resolve';
import commonjs from 'rollup-plugin-commonjs';
import livereload from 'rollup-plugin-livereload';
import { terser } from 'rollup-plugin-terser';
import { config } from '@sveltech/routify'
import copy from 'rollup-plugin-copy'
import rimraf from 'rimraf'
import path from 'path'
import postcss from 'rollup-plugin-postcss';
import alias from 'rollup-plugin-alias';
import svg from 'rollup-plugin-svg'
import autoPreprocess from 'svelte-preprocess';


const production = !process.env.ROLLUP_WATCH;

const { distDir, staticDir, sourceDir, dynamicImports: split } = config
const buildDir = `${distDir}/build`

if (!process.env.BUILDING) rimraf.sync(distDir)

export default {
	input: `${sourceDir}/main.js`,
	output: [{
		sourcemap: true,
		name: 'app',
		format: split ? 'esm' : 'iife',
		[split ? 'dir' : 'file']: split ? `${buildDir}` : `${buildDir}/bundle.js`
	}],
	plugins: [
		copy({ targets: [{ src: staticDir + '/**', dest: distDir }] }),
		svg(),
		alias({
			resolve: ['.js', '.svelte', '/index.js'],
			entries: [
				{ find: '@', replacement: path.resolve(__dirname + '/src') }
			]
		}),
		svelte({
			preprocess: autoPreprocess({
                postcss: true
            }),
			// enable run-time checks when not in production
			dev: !production,
			hydratable: true,
			// we'll extract any component CSS out into
			// a separate file — better for performance
			css: css => {
				css.write(`${buildDir}/bundle.css`);
			}
		}),
		postcss({
			extract: `${buildDir}/utils.css`
		}),

		// If you have external dependencies installed from
		// npm, you'll most likely need these plugins. In
		// some cases you'll need additional configuration —
		// consult the documentation for details:
		// https://github.com/rollup/rollup-plugin-commonjs
		resolve({
			browser: true,
			dedupe: importee => importee === 'svelte' || importee.startsWith('svelte/')
		}),
		commonjs(),

		// In dev mode, call `npm run start` once
		// the bundle has been generated
		!production && serve(),

		// Watch the `public` directory and refresh the
		// browser on changes when not in production
		!production && livereload(distDir),

		// If we're building for production (npm run build
		// instead of npm run dev), minify
		production && terser()
	],
	watch: {
		clearScreen: false
	}
}

function serve() {
	let started = false;

	return {
		writeBundle() {
			if (!started) {
				started = true;

				require('child_process').spawn('npm', ['run', 'start', '--', '--dev'], {
					stdio: ['ignore', 'inherit', 'inherit'],
					shell: true
				});
			}
		}
	};
}